[PATCH 6/9] Optimise __aeabi_ldivmod
Richard Earnshaw
rearnsha@arm.com
Wed Jun 18 14:03:00 GMT 2014
On 11/06/14 11:19, Charles Baylis wrote:
> 2014-05-22 Charles Baylis <charles.baylis@linaro.org>
>
> * config/arm/bpabi.S (__aeabi_ldivmod): Perform division using
> __udivmoddi4, and fixups for negative operands.
OK.
> ---
> libgcc/config/arm/bpabi.S | 41 ++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/libgcc/config/arm/bpabi.S b/libgcc/config/arm/bpabi.S
> index 3f9ece5..c044167 100644
> --- a/libgcc/config/arm/bpabi.S
> +++ b/libgcc/config/arm/bpabi.S
> @@ -175,10 +175,49 @@ ARM_FUNC_START aeabi_ldivmod
> test_div_by_zero signed
>
> push_for_divide __aeabi_ldivmod
> + cmp xxh, #0
> + blt 1f
> + cmp yyh, #0
> + blt 2f
> + /* arguments in (r0:r1), (r2:r3) and *sp */
> + bl SYM(__udivmoddi4) __PLT__
> + pop_for_divide
> + RET
> +
> +1: /* xxh:xxl is negative */
> + negs xxl, xxl
> + sbc xxh, xxh, xxh, lsl #1 /* Thumb-2 has no RSC, so use X - 2X */
> + cmp yyh, #0
> + blt 3f
> + /* arguments in (r0:r1), (r2:r3) and *sp */
> + bl SYM(__udivmoddi4) __PLT__
> + pop_for_divide
> + negs xxl, xxl
> + sbc xxh, xxh, xxh, lsl #1 /* Thumb-2 has no RSC, so use X - 2X */
> + negs yyl, yyl
> + sbc yyh, yyh, yyh, lsl #1 /* Thumb-2 has no RSC, so use X - 2X */
> + RET
> +
> +2: /* only yyh:yyl is negative */
> + negs yyl, yyl
> + sbc yyh, yyh, yyh, lsl #1 /* Thumb-2 has no RSC, so use X - 2X */
> + /* arguments in (r0:r1), (r2:r3) and *sp */
> + bl SYM(__udivmoddi4) __PLT__
> + pop_for_divide
> + negs xxl, xxl
> + sbc xxh, xxh, xxh, lsl #1 /* Thumb-2 has no RSC, so use X - 2X */
> + RET
> +
> +3: /* both xxh:xxl and yyh:yyl are negative */
> + negs yyl, yyl
> + sbc yyh, yyh, yyh, lsl #1 /* Thumb-2 has no RSC, so use X - 2X */
> /* arguments in (r0:r1), (r2:r3) and *sp */
> - bl SYM(__gnu_ldivmod_helper) __PLT__
> + bl SYM(__udivmoddi4) __PLT__
> pop_for_divide
> + negs yyl, yyl
> + sbc yyh, yyh, yyh, lsl #1 /* Thumb-2 has no RSC, so use X - 2X */
> RET
> +
> cfi_end LSYM(Lend_aeabi_ldivmod)
>
> #endif /* L_aeabi_ldivmod */
>
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